Banking Quantitative Aptitude Sample Paper Quantitative Aptitude Sample Paper-36

Simple interest on a certain sum is 16/25 of the sum. The rate per cent, if the rate per cent and time (in years) are equal, is                                                                                                                        [SSC (CGL) 2011]

A) 6%

B) 8%

C) 10%

D) 12%

Correct Answer: B

Solution :

Let the sum, \[P=x\]

Then, \[SI=\frac{16}{25}x\]and \[t=r\] [given]

By the formula, \[SI=\frac{P\times r\times t}{100}\]

\[\Rightarrow \] \[\frac{16}{25}x=\frac{x\times r\times t}{100}\]

\[\Rightarrow \] \[{{r}^{2}}=64\]\[\Rightarrow \]\[r=64\]

\[\Rightarrow \] \[r=8%\]per annum

Alternate Method

If SI is \[\frac{x}{y}\]part of the principal P at the rate of r% per annum in \[t\,\,yr,\]also \[t=r\]

Then, \[t=r=\sqrt{\frac{x}{y}\times 100}\]

Here, \[\frac{x}{y}=\frac{16}{25}\]

\[\Rightarrow \] \[r=\sqrt{\frac{16}{25}\times 100}\]

\[=\sqrt{64}=8\]%per annum